TY - JOUR

T1 - Available dissolved organic carbon alters uptake and recycling of phosphorus and nitrogen from river sediments

AU - Stutter, M.

AU - Graeber, D.

AU - Weigelhofer, G.

PY - 2020/11/26

Y1 - 2020/11/26

N2 - Concurrent with nutrient pollution, agriculture has significantly impacted the quantity, composition, and bioavailability of catchment-derived dissolved organic carbon (DOC) in stream ecosystems. Based on the stoichiometric theory, we tested the hypothesis that bioavailable DOC will stimulate the heterotrophic uptake of soluble reactive P (SRP) and inorganic nitrogen in stream sediments. In a simplified laboratory column flow-through study, we exposed stream sediments to additions of glucose, nitrate, and phosphate alone and in combination (+C, +NP, +CNP), and calculated gross and net changes in DOC and nutrients via a mass balance approach. Our results show that glucose-C increased nutrient uptake, but also that NP additions resulted in the enhanced consumption of both native and added organic C. The effects of C addition were stronger on N than P uptake, presumably because labile C stimulated both assimilation and denitrification, while part of the P uptake was due to adsorption. Internal cycling affected net nutrient uptake due to losses of dissolved organically-complexed P and N (DOP and DON). Overall, our study shows that increases in the stoichiometric availability of organic carbon can stimulate N and P sequestration in nutrient-polluted stream sediments. Future studies are required to assess the effects of complex organic carbon sources on nutrient uptake in stream sediments under different environmental conditions, and whether these stoichiometric relations are relevant for ecosystem management.

AB - Concurrent with nutrient pollution, agriculture has significantly impacted the quantity, composition, and bioavailability of catchment-derived dissolved organic carbon (DOC) in stream ecosystems. Based on the stoichiometric theory, we tested the hypothesis that bioavailable DOC will stimulate the heterotrophic uptake of soluble reactive P (SRP) and inorganic nitrogen in stream sediments. In a simplified laboratory column flow-through study, we exposed stream sediments to additions of glucose, nitrate, and phosphate alone and in combination (+C, +NP, +CNP), and calculated gross and net changes in DOC and nutrients via a mass balance approach. Our results show that glucose-C increased nutrient uptake, but also that NP additions resulted in the enhanced consumption of both native and added organic C. The effects of C addition were stronger on N than P uptake, presumably because labile C stimulated both assimilation and denitrification, while part of the P uptake was due to adsorption. Internal cycling affected net nutrient uptake due to losses of dissolved organically-complexed P and N (DOP and DON). Overall, our study shows that increases in the stoichiometric availability of organic carbon can stimulate N and P sequestration in nutrient-polluted stream sediments. Future studies are required to assess the effects of complex organic carbon sources on nutrient uptake in stream sediments under different environmental conditions, and whether these stoichiometric relations are relevant for ecosystem management.

KW - Column experiments

KW - Macronutrients

KW - Stoichiometry

KW - Stream sediment

KW - Agricultural robots

KW - Biochemistry

KW - Catchments

KW - Dissolution

KW - Ecosystems

KW - Glucose

KW - Nitrogen

KW - Organic carbon

KW - Phosphorus

KW - River pollution

KW - Sediments

KW - Stream flow

KW - Dissolved organic carbon

KW - Ecosystem management

KW - Environmental conditions

KW - Inorganic nitrogen

KW - Laboratory columns

KW - Nutrient pollution

KW - Soluble reactive P

KW - Stream ecosystems

KW - Nutrients

U2 - 10.3390/w12123321

DO - 10.3390/w12123321

M3 - Journal article

VL - 12

JO - Water

JF - Water

SN - 2073-4441

IS - 12

M1 - 3321

ER -